Method of making patterned foil webs



Nov. 5, 1968 P` EISLER METHOD OF MAKING PATTERNED FoL WEBS 5 SheetS-Sheet 1 Fi1ed Nov. 29 1965 Nov. 5 1968 P. EISLER 3,408,735

METHOD OF MAKNG PATTERNED FOI WEBS Fj 1ed Nov 29 1965 5 Sheetssheet 2 Nov. 5, 1968 P. EISLER 3,408,735

METHOD OF MAKNG PATTERNED FOL WEBS Fi1ed Nov. 29 1965 5 Sheetssheet 5 Nov. 5, 1968 P. EISLER METHOD OF MAKNG PATTERNED FoL WEBS Fied Nov( 29 1965 7 versed i e. the foil is Ilot unfolded back into itS riginal )()siti0l TO permit adjustment of the loughs, they are Slotted and held by bolts 112 t0 their Support 113.

The gure shows the Toller 104 running against the l'0lle1 103 but they could be slightly Spaced, the Shoes being correspondingly Shaped In the example, endless rubbercovered wires 114 run over 100Se discs 115 in the gr00ves in the r0ller 103 and over a guide T0ller ll Vvhile a pressure T01ler 117 Squeezes the rubbef gainSt the foil passing over the roner 104 after it has left the shoes 111, and thus C0Inpletes the attening of the f01ded Inargins Instead a Simple pressure Toner might be used, but both thes devices can be on1itted if the shoe is Shaped t0 c0mplete the attening( Also as explained belovv With reference t0 FI(...IJRES 12 and 13 the ploughs and Shoes caT1 be Supplenented 01 replaced by pneuInatic tneans.

If a pattem With the minimum Width of aTm is to be produced there is a knife and plough in every groove 0f the roller 103 but for vvider arIns a corfesponding numel Of gr00ves is left Without knives and ploughs. Thus arms of a width of any multiple of the minimum ca`1 be produced 011 the sanle machine without changing the grooved Tollers, Inerely changing the number of knives and ploughs. 1/I()(1ifi(;ati01s of details Of the machine aTe possible Thus the knives might be set at the angle indicaed for the active position in FIGURE 3 and be Inoved only longitudinany to bring them int0 the inactive o- Sition.

After being crimped between the Touers 105, which may be constructed to leave an uncrimped zone 0r Zones With the crimps 180 Out of phase on the opp0site sides of such a Zone if necessary, the attefn and crin]ped foil has the insulating covering l@8 laminafed to it While passing over the drum 107 Which may be heated or Water cooled according to the requirel11ents of the laminating rocess 'I]is drum 107 iS desirably adjustable a little t0- vvards aTld away fr0m the 10Wer Toller 106 in order to prestress the crin1ped f0il if the insulating covering 108 is not elastomeric On its Way to the drum 107 the foil ol the covering 108 n1ay be coated and dried if 1ecessary. 'lhe covering is led to the druIn over a tensi0n contr01ling Toller 118' It will be seen that the foil 101 lies on top of the covering 108 vvith its1acquered Surface tovvards the latter. 'lhe bre foil Surface is contacted by the crin^lping '()llel' 10 and a1SO by two further nletallic rollers 119 and 121' The rouers 106, lz1 are earthed while the T0ller ll iS connected to the live pole of a Supply So that current OvvS longitudinally through the f0il fr0m the roller ll to both the rollers 106 and 121 and there by heats the` f0il Suiciently t0 eect a. j0int betvveen the foil and the covering 108 Which ale held pressed t0- gether by their path round the drum 107. Some adjustn]ent in the heating eect can be 0btained by displace ment 0f the rollers Which Supply the current, conveniently by mounting the rouers ll9, lzl S0 that they can be dislaced round the axis of the drum 107. on itS path fr0m the roller 121 to a further Toller 122 the iilm is c00led and nlay pass to a rereeling Toller or t0 a Coating 01' covering Station at vvhich the bare Surface iS insulated' It wm be clear that instead of using the crimping roner 106 as one of the connecting 1Ileans in this heating arraT1gement, a Separate roner may be used and that instead of using Tollers fol 1T1aking contact Tods could be 11Sed.

T0 roduce the pa(tern of arms aS in FIG 1 it is sumcient t0 divide the knives l@ int0 two groups of alternate knives and lift each group int0 its inactive p0sition Separately to leave the bridges Any convenient n1eans Inay be 11Sed for d0ing this, f01 example, a solenoid ()l air cylinder for ech group controlled through switches theIn Selves operated by a multiple (and referably adjustable) cam geared t0 the T0ller 103- If n10re elaborate patterns are t0 be nlade e...fch knife n1ay be individuauy ]ifted into inactive position and 10Wered int0 active OSition by a separate Solen0id, aif cylinder 01' 0ther device the pattern being deternined by a Pattern card 01 the like, after the fashion of a Jacquard, hich may be sensed electricany or phot0electrica11y, or a moving n1aster pattel'n geaTed to the T01ler and Similarly Sensed nlay be used. It is als0 desirable t0 impart to the knives a cyclic longitudinal Inotion, thereby to even out the Weal' On their cutting edges. The mechanism Which 1ifts and 10Wers them can incorporate a linkage Which does this.

If necessary or desirable the foil may be lubricated bef0re slitting and folding as described later With Tefer ence to FI(JRES 8 t0 18 using a lubricant of the char cter also described later.

AS Shown in FIGURE 4 the knives are ro ortioned S0 that the Slit is made midway between the walls of the groove iIl the T0ller 103. Thus the n1argins folded over on 0pposite sides are of equal width; The edge of the knife n1ight however be 2Symmetrically disposed giving dierent vvidths Of n1argin on opposite sides, OI' even aS indicated in FIGURE 7 be at the Side Of the knife Which iS here mark d l09. In this caSe the Slit iS made by Shearing in conjuncti0n With the edge Of the right hand Wall of the gr00ve S0 that n0 f01d iS made here While the margin on the other side Which is folded 0Ver has a Width equal to the totl Width of the groove 'Ille parts of the Shoes 111 Which project int0 the Space between the rollers 103, 104 and vvhich SeTve to continue the f0lding beyond need only be Shaped for the purpose on the one Side It Will be cleaT that in the machine above described vvith Teference to FI(S. 3 to 6 the Slit is Started 'by inserting the knife int0 the gr00ve and the Slit iS ended by lifting the knife out of the g00ve Straight knives are therefore preferably made With a Sharp point which can be moved in aln10st perpendicular difection int0 and out of the foil.

The knives could be n10ved iI1 a cycle during Which the incision is staTted by advancing the knife point into the groove and the incision iS completed and the interruption produced by vvithdrawing the knife fronl the gr00ve. By suitably contr011ing the cycle of the knife and suitably Shaping the knife )0int, during the Withdravva1 0T entry Of the knife point when the incision is terlninated or commenced, it can be arranged that the longitudina1 c0m ponent Of the speed of the cutting edge Of the knife iS relatively equal to the speed Of the vveb and the Telative move- Inent between the cutting edge 0f the knife and the vveb iS SubStantilly perpendicular t0 the vveb The cycle of movenlent can provide for the knife to be Tnoved 10ngitudina]1y aS We11 as With a Tadial conp0nent relative to the grooved Support. In thiS case the knife can be fegarded aS a gapped knife, in eect the gap in the cutting edge being simply the space beyond the knife point The two phases of the cycle of movement of the knife Inay be controlled S0 that the phase 0f the movement when the knife is clear, bears a fixed relationship to the movement of the Web t0 give a fixed length of interruptions aIld S0 that during the incision phase the movement of the knife iS contr01lable independently 0f the movement of the web t0 give a length of incision vvhich can be varied. Thus the knife Inay be Inoved by the aid of relatively adjustab1e cranks and adjustment of the web feed as described be10w.

I1]Stead 0f using Straight kniveS rotary circular knives could be used in the above desc ibed machine, the knives being lifted at the requisite intervals to produce the bridges, and the knives als0 Serving to effect the first 90 ()f f01ding Such knives could r0tate vvith a periphera1 Speed equal to the Speed of the web or at a different Speed' The same basic method of Slitting and folding underlies the a aratus shown in FIGURES 8 to 18 but rotatin circular knives With gapped cutting edges are here llsed vvhich have an]ong other advantages that they d0 I10t have t0 be raised t0 leave the uncut bridges, these here being produced by the gap in the cutting edges of the knives AS win be explained, not only can this apparatus produce a meander pa[terned f0i (including the folded n]argins) at high Speed Witha femarkably Snall incidence 0 failis urged towards the shaft, and the bent over portions 324 bear against the shaft, S av0iding any 100Seness.

Since with this construction of the Shaft 319 aternate knives a re threaded from opposite sideS, it iS essentia1 that the number of gaps in the knife Should be 0dd, Other- Wise the gaps in one knife v ould come in line with gaps in the adjacent knives and not midway between, as is Tequired t0 produce a meander pattern` If sonle 0ther Section of shaft, e-g trianguar, vvere used, Which enabled the alternate knives t0 be threaded at angles Which are an odd Sub-multiple 0f 30", then an even number of gaps in each knife Could be pr0vided, but not a Single gap 'lhe clltting edge and some Width Of the full thickness of each knife penetrates into a c0rresponding gr00ve 326 in a grooved roller 327. The spacing centre t0 centre 0f the gr00ve 326 is equal to the minimum spacing centre to centre of the Slots of the pattern and corresponds to the minimum width of the arms of the pattem During threading On of the knives glliding of them int0 the Sts is facilitated by rods 328 Supp0rted on a bar 329 thus forn1ing a comb-like guide( There is one rod 328 in line with each part of the roller 327 betvveen the gr00ves 326, and they assist in guiding the knives and reventing binding of the knives against the Sides of the gf00ves 3z, the greater part of which are only of Such Width as t0 give Small clearance t0 the knives, See FI(...IJRE 14 Additiona1 comb guides can be provided at other p0sitions round the Shaft 319 S0 that the knives are retained ac- Curately on planes perpendicular t0 the axis of the grooved roller 32 ()ne Such further guide c0mprising rods 331 and a bar 332 is Shown in the drawing8- The comb guides themselves may be 10cated axially by a part on the guide engaging a gr00ve in the roller 327, thls ensuring the correct alignment in felation t0 the gr00ves' AS before a knife can be mounted for every groove, every Second gr00ve, every third groove etc t0 enable arm widths of the minimum or mu...ples thereof to be 0btained 0f the minimum or multiples there0f to be obtained.

obviously, Since the gr00ved roller 327 is cylindrical, all the knives must be of the Same diameter, but they need not all have the sane number of gaps. F0r exarnple, in a Wide machine it may be desired t0 Inake Several different patterns side by Side over dierent parts ()f the Width of the veb. Then there nlay be a group of knives with Say one gap, an0ther group of knives With say three gaps, and another group With Say Eve gaps Comparatively large spaces may be left between the dierent groups to provide uncut margins of web between the corresponding patterns of Slits subsequent]y, the Web may be slit continuouSly along the centre line Or other OSition within each vide unpatterned Zone t0 separate the Several patterns, but in other cases there may be diiferent pattern distributions for dierent Surface loading in dierent zones of the width It will be underst00d that Where Several dierent pat terns are pr0duced in this way, the cycle of In0tion of the knife Shaft and Tati0 0f the gear 318 must be Suited t0 the lowest c0mmon multiple of the various number8 0f gaps, S0 that the correct Speed of the knive8 is obtained whenever a gap iS Passing over the vveb I`here will then be an acceleration and deceleration between every gap passage over the web during one Tevolution of the Shaft, but this will not interfere With the adjustlnent of the de- Sirgd lcngth of incision Which will Still depend on the adjustment of the slide 30.

l'he web 333 PaSSeS Over the roller 327 and thence over a plain T0ller 334 having itS periphery C10Se to that of the rouer 327. From the roner 334 it passes t0 the feed and crimping rollers 304. During passage over the roller 3z7 the Web iS Slit and the margins folded over through 90 by the coaction of the knives and foller 326 jllst as in FIGURES 3 to 6 above described' Due to the nafrow clearance betvveen the knife 3zl and the Walls of the 12- gr00ve 326, a recess 335 is provided on each sid( to ac con1modate the thickness of the vveb.

T'0 prevent the folds produced by the action of the knives fron1 unfolding vvhen the folds have Inoved clear of the knives, plough Inenbers 33 vvhich project int0 the Space between the roners 327 and 334, and extend along the gr00ves to a P0int near the knives, hold the folds in Place, These ploughs Widen into shoes 337 in the Space betvveen the Tollers, and con1plete the f01ding over of the margins back on t0 the Web These Shoes are Shaped to allow free passage to the uncut bridges in the vveb. Practical considerations Inay Inake it dimcult t0 carry the p10ughs 336 C10Se enough t0 the knives, and a pneufnatic means Such aS a jet of air delivered t0 this Zone by a nozzle 336 n]ay be used to hold the 90 f0lds in place' It Should here be mentioned that if the web iS a plain Inetallic foil, the difHculty of a tendency t0 unfold may not arise, but if for example a foil has been laminated to a layer of paper, aS described be10w, there is a mOe S riOUS risk of a tendency to unfold Ail' jets may be reHed on t0 hold the 90 folds in lace all the Way t0 the point where the Web leaves the roner 3z7, S0 that the p10ughs can be Onitted and only shoes be provided. It Would even alSo be p0ssible t0 replace the ShoS by air jets. Cases may arise in Which it iS not desired to c0m plete the folding, but t0 au0w the 90 folds to unfold themselves under the elasticity 0f the materia Of the Web' In that caS the mechanical folding means constituted by the ploughs 334 and shoes 335 are taken out of action Suitably by mounting these arts S0 that they can be Swung about the axis of the roller 327, as indicated by the arrow' Taking of theSe parts out of action may als0 be necessary if a fault Occurs whlch threatens to ]ead t0 tearing of the Web or ianming Pneumatic n]eans can be put out of CtiOn Simply by cutting 0 the air Supply.

with the Shaft 306 aligned With the input Shaft to the gear 318, the coupling constituted by the crank arms 308, 317 and the pin 316 causes these two Shafts t0 rotate in exact Synchronisn1 and if this speed iS appr0priate, the peripheral Speed of the knife iS equal to the Speed of the Web; these tvvo Speeds 'are both derived fron1 the Same source 301 and the gearing 302, 303, 305 detern1ines their relationship' If now the slide 30p is adjusted So that the shaft 30 is no longer aligned With the.input shaft to the gear 318, although the two crank arms 308, 317 are still positively coupled by the pin 316 S0 that they must rev01ve at the 'Sanle mean speed, it vvill be clear thattheir Telative angular ve10city must vary throughout a single revolution' Thus if as vvill be ISllal the Shaft 306 and arm 308 rotate llif0rn1ly the arm 317 and the parts driven thereby Will rotate non-uniforn]1y. The variation Will be Sm00th and the cycle will include a phase 0f acceleration and a phase 0f deceleration. At the tW0 points in the cycle at Which there is a change fr0m acceleration to deceleration and vice versa, the angular ve10city of the arm 317 vvill be practica11y constant over a Short period and the tin1ing in relation to the shaft 319 is arranged S0 that the gaps in the knives are passing over the Web during one 0f these periods. Further the coupling Of the adjustInent of the gear 305 With that of the slide 30 can he arranged so that in all p0sitions of adjustment the peripheral Speed of the knife duTing these periods Win be the SaIne, S0 that the interruptions Wiu always be of the Same length and the adjustment of the `Slide will only change the length 0 the Slits. The speed of the knife at the passage of the gaps is preferably equal to the speed of the Web. (Strictly it can Only be equal at one instant or at tvv0 instants vvhich can be chosen to synchronise as nearly aS 0sSible with the terlnination and Start of the incision.) Depending on Which transition OcculS at the passage of the gaps the Slit vvill be Shortened or lengthened aS c0mpared vvith constant Speed and if the adjustment of the Slide 3 can carry the one shaft to either Side of the 0ther a change 13 TOn1 a Shtr cut t0 a longer cut than that`given vvhen the shafts ale aligned can be obtained.

In the I!achine aS S0 fal described, the feed of the web is impaed S0lely through the rollers 304. Ile web comes fl()m asupply in Ton form indicated at 33, and the necessary tension is i! )arted by friction bars 341, be*fore it passes over the T01lers 327 and 334 Which are rotated by the web itself as by this means the fofces which' the Inechanically dtiven parts exert of the web on (Ile one hand-and the strength and dynamic force of the web itself, are balanced( There is a lower limit to the strength of the Web, with which this balancing of forces can be achieved If the web iS thinner than this linit, a complex electronically controned drive can be used Preferably, however, if the web is t00 vveak, being for instance a very thin metallic f()il, it may rSt be laninated at least on one side to a Suporting Inaterial Such as paper 01 a mmof Syntheti( ma terial, or 'be given a coating qf varnish or he like( f such a layer is used on one Side only, it is preferably arranged S0 that it is on the outside when the Web is paSsi 1g over roller 3z, as in that case Yhen the nargins are folded 0ver, this insulating layer vvill be on the outside and th condilctive web in the folds will have the folded over nlargins in face to face contact' AS Shown in FIGURE 7 and as above described, the knives are 0f Syn1metrical section, and the f0il is Slit midvvay over the g100ves 326, S0 that equal Inargins are folded over on the Sides of the slits. In particular cases, it may be desired to nlake the knives of asymmetric Section, S0 that unequal Inargins are f0lned, 0 even aS Shown in FIGURE 9 to make the knives of Such section that the cutting edge 0f the knife 3zl iS vvhony t0 0ne Side. Then only one IIlargin vvill be folded Qver, and ther6 need be only one Tecess 33S(Z.

AS above described, the interruptions or bridges extend in a line perpendicular t0 the length and direction 0f the Inovement of the vveb, and each repeat pattern is of gen erally Tectangular outline It nlay be desi ed that the bridges Should extend across at a Slope or in other vvords that the geenral outline 0f each repeat Should be a nonrectangular parane10gram. Ihis can ready be achieved by making the shaft 319 a steep hencal form If it is de- Sil`...d to be able to adjust the helix angle, the Shaft may b6 made eible in torsion.

One arrangement is shown as FIGURE 10. The shaft hre compfises an innel nernber 31 and an outer member 319, vvhich consists of a spiral spring vvith Square shaped turns seated on the inner mernber 319' The Spring is desirbly made of rectangular section strip vvound With th6 turns cloSe together such a spTing can be tvvisted In0Te or less, and is provided vvith S0Tle means for locking it, for exa[nple by c0mPeSSi0n from the ends between a shoulder and a lut. The member 319 can be Solid 0 hollow.

Another ossibilit is illustrated in FIGURE 11. Here, the shaft itSelf is Springy, being made up of a pack of thin leaf spfings 3l9c, these being well lubricated. For the Sake of clearness, the springs a[e Shown thicker than Would actuany be used, and there would therefore be a larger number of then. Again, Sonle means is pfovided for locking the Shaft when the necessary tvvist has been imparted For example, the Shaft at p0ints bey0nd the length which carries the knives may have keyed to it a gear Wheel These gear Wheels mesh With tw0 0ther gear wheels keyed to a Shaft iournalled to be free t() r0tate vvhich can be Inoved t0 unnesh the vvheels vhile they are unmeshed the desired twist is imposed on the Shaft and the yvheels are then e-meshed, thus Inaintaining the desired angular relationship between the ends of the Shaft The gear Wheels must be 0f Such Size tha the Sec- 0nd mentioned Shaft clears the knives and any other part of the apparatus which might 0therwise be in the Way. Alternatively, a circular Section, Solid or honow Shaft 14 could traverse the pack of leaf Springs and carry IJ-clips, Which after adjustment of the twist can be locked on the ends of the pack of leaf sp1ings by the action of a shoul der at one end and a nut at the o her.

with these adjustable shafts, the s10ts 3zz in the knives are nlade a Se fit SO that they can accommodate a Tange of twist of the Shaft With Such twisted Shafts the exact phase relati0nship of the gaps to the n10ti0n cycle will vary along the shaft, S0 that there will be a variatiqn in th6 length of the bridges across the web 'but it wm be very Small in Practical Cases and is kept t0 a minimum by arranging that the knife at mid-length of the Shaft is correCtly phased.

1IO e elaborate variations of the pattern of bridges can be achieved by 0ther forms of Shaft having the cT0SS Sc tion by vhich the angular disp0sition of the knives iS de ternined varying or variable along the length of the shaft Such a Shaft may have the angular disposition va ying or variable in Steps equal to the minilllum spacing of the knives Such a Shaft may be made up 0f rectangular blocks threaded in a central Shaft t the desired hase angles and clanped together, aS by a sh0uldr at one end and a nut at the 0the1. In 'such a case if the total phase variation is Substantial, it vvill be best to rotate the shaft at constant Speed and accept the pr0portionate change in the length of the bridges or cor1'ect these by using knives With variable gaps aS in FIGURES 10 and 11 Where adjustment is made between the relative Speed of the shaft and Web to change the length of the Slits, aS described above with reference to FIGURES 5 and 6. In some cases, however, it Inay be possible to use a repeating cycle of In0tion er Tevolution vvhich gives constant bridge length with Vafiable SHt ength The various parts of the machine are arranged to facilitate exanination and exchange. AS above explained, the knives are easily renloved and Teplaced individuany, for exan1p1e, for resharpening The Shaft unit as a vvhole Can' be n10unted S0 that it can be moved towards and away from the roller 3z( The Inounting of the ploughs and Shoes enables then1 t0 be adjusted and also enables them to be Inoved into a position in Which the operative ends are accessible for examination Slitting and folding can be facnitated by lubricating the vveb This can conveniently be done by a roller 34z p0sitioned near the tensioning baS 341. fter the pat terned eb has emerged from the crimping roners 304 it nlay pass to equip[nent such as that described above vvith reference to FIGURES 3 t0 6 for lamination to other materials' In this case, the lubricant should be c0mpati ble With the materials vvith vvhich the vveb is coated or laminated before or f0]1()ving Slitting It Inay be a liquid vvhich can be driven Off by heat when the web elnerges from the crinlping rollers 34 or -vhich could serve as a Solvent or plasticizer of the Solid content of an adhesive by Which the subsequent lanination is effected, or be a S01' vent or plasticiser of or othervvise c0npatible vvith a plastic lm t0 vvhich the vveb iS Subsequently laninated.

It is to be undestood that in this specicati0n "cTimp ing" means having undulations disp0sed perpendicular1y to the general Surface of the foil and 0f suchcharacte that there is Substantially n0 change in the thickness of the f0il vvhen the crimping iS eected. 'lhis form of crimping is in itself known and can be e{fected by running the fon between tvv0 rollers having intermeshing teeth of pitch appropriate to the pitch of the crimps desired' Such crimping confers extensibility t0 the foil -far beyond any such quality p0ssessed by the f(il in the at and it enables the foil to be distorted somewhat in its own place without darnage and generally t0 be handled without damage n0twithstanding its thinness What I claim is:

1. A method of producing a Series 0f interrupted longitudinal slits of varia-ble length in a web, Without the need to exchange the cutting tool and without the need t0 keep a constant relation between the length Of the Slit and the length of the interrupion, including he Steps of feeding the vveb longitudinally througha clltting station, and While the web is in motion through the Station, imparting a repeating cycle of ihovements"t knife having a cutting edge With at leastone gap threin, Said cutting edge being disposed in a longitudinal plane, Said cycle including a n10vement of the knife in Said 10ngitudinal ane in nxed Tatio to the m0ven1ent of the vveb While the gap in the cutting edge iS assing over th web and a movement of the knife in Said longitudinal plane contronable independent1y 0f the n10vemen't- 0f the web while the cutting edge makes an incision in-the Web z. A nlethod as Set Orth in clai l l in Which during that phase of the cycle in Which the gap is pasSing Ovci the web, at at"least one end of the incision, the`lOngi tudinal conlponent of the Speedof the knife iS Substanti ally equal t0 the Speed of the web lnd the Telative move- Inent between the cutting edge of the knifd and the veb is Substantially perpendicular to 'the vveb 3. A method as Set forth in claim l in Which during the phase of the cycle in Which the knife is making the incision, at least one acceleration and one deceleration are included in the movement of the knife 4. A method as Set forth in claim l in whiCh` the motion imparted t0 the knife iS always in the Same direction during at least one cycle Whereby the incision is started by one end of the cutting edge and terr[1inated at the other end of the cutting edge, vvhile provision iS made to regulate the n1ean Speed of the knife during the cycle in felation to the Speed of the web.

5 A method as set forth in claim 1 Which includes prior t0 the incision Of the vveb, the step of reinforcing the Web by adhesive application of another material to substan[iauy the Whole area ()f the Web.

A method aS Set forth in claim l is Which the web iS held under tension during incision.

7. A method as set forth in claim 1 Which includes prior to the incision of the web, the Step of lubricating the Web vvith a lubricant c0mpatible with any 0ther 1Tlaterials With vvhich the Web is in adhesive surface contact during the conlplete cycle of operations 8 A method aS Set forth in claim l in which the Web is Supported at the cutting Station by a grO0ved Support with substantially square corners at the groove openings, but the knife is carried far enough through the vveb and into the groove to fold at least one margin of the web through an angle not exceeding 90 degrees and thereafter While the f0lded Inargin is still ih the groove, the web is carried into the Held of action by means capable of continuing the folding of such margin, Such nleans being controllab]e in the extent of itS action on the folded margin A method aS Set forth in claim 8 in Which said means conTpletes the folding over of the nargin t0 a position paranel with the unfolded part of the web, thereby converting the slitSinto slots 10' A method of pr0ducing a meander pattern in Which a plurality Of Similar Series ()f slots are Simultaneous]y 639 206 12/l936 Germany. 

